# Investigating Why Transmission line Voltage is in multiple of 11

### Why Transmission line Voltage is in multiple of 11

In this article we are Investigating Why Transmission line Voltage is in multiple of 11. So, you must have heard that this transmission line is of 11kV (11000V), it is 33kV, 22kV, or 33kV….etc. so friends, have you ever wondered why it is in multiple or coefficient of 11, so let’s know.

### Transmission Line Voltage

First of all, let us tell you that not all the voltage of the transmission line is in multiples of 11. Transmission line voltage is 11kV, 22,kV, 33kV, 66kV and 132kV apart from 400kV, 765kV and 800kV which is not 11 multiple.

Image credit: electricalnotebook.com

### Due to form factor

In many places you must have heard the answer to this question that transmission line voltage is due to the multiple form factor of 11.

Let us understand below.

The value of the form factor is 1.1. Because the Form factor is the ratio of RMS and the average value of voltage or current.

Form factor= Vr.m.s / Vavg

Vr.m.s= Vm / √2
&
Vavg= 2Vm / π

Form factor= (Vm/√2) / (2Vm/π)

Form factor= Vmπ / √22Vm

Form factor= 1.11

Now if we multiply this 1.11 with the line voltage then below are some conclusions-

10kV x 1.11 = 11.1kV
20kV x 1.11 = 22.2kV
30kV x 1.11 = 33.3kV
60kV x 1.11 = 66.6kV
120kV x 1.11 = 133.2kV

But the transmission line voltage is not 133.2kV ​​but 132kV.

Therefore, there is no multiple of 11 in transmission line voltage due to form factor.

### Due to voltage drop in transmission line

Let us tell you that when Thomas Edison did electricity transmission for the first time in the history of electricity, he had to transmit more than 100V to get exactly 100V.

This happens because the transmission line has some losses of its own, due to which the voltage we receive is always less than the transmit voltage.

Engineers studied this and told that the voltage loss in the transmission line is about 10%. Perhaps 10% would have been done to make the calculation easier, the exact value could be 12 or even 8.

10% of Transmit Voltage

10kV x 10% = 1kV
transmit voltage = 10+1 = 11kV

20kV x 10% = 2kV
transmit voltage = 20+2= 22kV

30kV x 10% = 3kV
transmit voltage = 30+3 = 33kV

60kV x 10% = 6kV
transmit voltage = 60+6 = 66kV

120kV x 10% = 12kV
transmit voltage = 120+12 = 132kV

200kV x 10% = 20kV
transmit voltage = 200+20 = 22

#### Higher Transmission Line Voltage – 400kV, 765kv and 800kV

10% line loss is not taken for transmission voltage higher than this because the higher the line voltage, the less the losses keep on decreasing.

That’s why Transmission voltage 400kV, 765kV or 800kV is not in multiples or multiples of 11.

So friends, now you must have understood why Transmission line voltage is in multiple of 11, so it is taken because of the loss in Transmission line.

### What is a transmission line?

A transmission line is a specialized cable or conductor used to transfer electrical energy or signals from one location to another, typically over long distances. It is an essential component of power distribution and telecommunication networks.

### What are the main types of transmission lines?

The two main types of transmission lines are:
a. Power Transmission Lines: These lines carry high-voltage electrical power from power plants to substations and from substations to distribution networks.
b. Communication Transmission Lines: These lines carry signals for data and communication, including telephone, internet, and television signals.

### How are transmission lines different from distribution lines?

Transmission lines are used to transmit power or signals over long distances at higher voltages, while distribution lines distribute power or signals at lower voltages to end-users in local areas.

### What are the factors that determine the efficiency of a transmission line?

The efficiency of a transmission line is influenced by factors such as line length, conductor material, insulation, and the quality of insulators used.

### How are power transmission lines insulated?

Power transmission lines are insulated with materials such as glass, porcelain, or composite insulators. These insulators prevent electricity from leaking to the ground and help maintain the safety and reliability of the transmission system.

### What is the significance of the voltage level in power transmission lines?

Higher voltage levels are used in power transmission lines to reduce power losses during transmission. Increasing the voltage allows for the same power to be transmitted with lower current, reducing resistive losses in the conductor.